The present invention relates to a method for controlling nitrogen oxides levels in flue gases generated in refinery processing, and specifically in fluid catalytic cracking systems. More particularly, the present invention provides a process for reducing the NOx content of FCC regenerator flue gas in the presence of sulfur oxides by contacting the flue gas with an additive comprising a perovskite, a spinel, and optionally a stabilization component and a cracking component.